Iron sharpeneth iron; so a man sharpeneth the countenance of his friend.
Fellowship (or contact) with other Christians is a very important aspect of the Christian life. It keeps us well-rounded. Just as when two pieces of rusty metal are rubbed together, the contact surface becomes clean and shiny and smooth, so it is with Christian fellowship. A recluse is a very lopsided person. Never shut yourself away in seclusion, but cherish contact with other believers to help rub off the rough spots in your personality and viewpoint.